The burden of proof is the responsibility of proving a point which is at issue between contending parties, as in a lawsuit. This is in contrast to a debate, in which each party must support his contentions.

In certain types of a dispute the status quo is often accepted as the norm, and defenders of the norm need not prove that it is true. Challengers to the norm have the burden of proof.

In polite debate, the person making an assertion carries the burden of proof - after all, no debate can begin unless the person provides ground for debate. Without evidence provided, an assertion can generally be rejected out of hand.

In some forums, the burden of proof is reversed, and an assertion is allowed to stand unless disproof is offered. Complaints against this sort of thing in jurisprudence led to the American standard of "innocent until proven guilty."

In debates about religion, atheists will frequently argue that theists have the obligation of proving God's existence, and atheists have no obligation to prove everything. Atheists will frequenly reference the following passage by philosopher Bertrand Russell:

Many orthodox people speak as though it were the business of sceptics to disprove received dogmas rather than of dogmatists to prove them. This is, of course, a mistake. If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed even by our most powerful telescopes. But if I were to go on to say that, since my assertion cannot be disproved, it is intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense. If, however, the existence of such a teapot were affirmed in ancient books, taught as the sacred truth every Sunday, and instilled into the minds of children at school, hesitation to believe in its existence would become a mark of eccentricity and entitle the doubter to the attentions of the psychiatrist in an enlightened age or of the Inquisitor in an earlier time.

However, Russell's example fails to prove what he claims to prove. We have good reasons to suppose the teapot could not possibly be in such an orbit - how could it have gotten there? Given our knowledge of the laws of nature, the teapot could only be in such an orbit if someone had placed it there; given our knowledge of human history, we can be confident that no one has yet done so (either in our day or Russell's); although, in centuries to come, someone may well put one there. By contrast, we do not have good reasons to suppose that God does not exist. If the atheist wishes to disprove the existence of God, the atheist is required to provide evidence for God's non-existence, in the same way as the religious believer can provide evidence for God's existence. If we truly have no evidence, the correct answer is not atheism, rather it is agnosticism. In any case, there is a logical difficulty in any atheist trying to argue from the burden of proof — the burden of proof is a basic principle of rationality, but different people understand it differently. Lacking any objective standard of rationality, the atheist has no way of deciding whose understanding of the burden of proof is right. By contrast, the religious believer believes there is an objective standard of rationality, the nature of God, which we can turn to in order to seek answers to such questions concerning whether God exists.

Latin versions

The burden of proof is traditionally associated with the Latin phrases "actori incumbit onus probandi" or "semper necessitas probandi incumbit ei qui agit", both meaning: The burden of proof rests on the party who advances a proposition affirmatively[1]